Fuel-control system



. 1,627,341 y 2 e. A. ROBERTSHAW FUEL CONTROL SYSTEM Filed Jan- 29. 1926Patented May 3, 1927.

UNITED STATES GEORGE A. ROBERTSHAW, OF GREENSBURG, PENNSYLVANIA.

FUEL-CONTROL SYSTEM.

Application filed January 28, 1926. Serial No. 84,745.

The present invention relates broadly to an improved system or apparatusfor governing the flow of fuel to a burner, and more particularly to asystem employing a novel arrangement of diaphragm valves for controllingthe passage of gas.

At the present time diaphragm valves are being used to a considerableextent in connection with the control of gas to a burner. In spite ofthe rapiditywith which it has heretofore been possible to operate suchvalves whereby a true snap action has been attempted, the valves havemet with the objection that they do not constitute a means of control ofthe true snap action type which is efiective either for permitting afull flow of the gas or cutting off such'flow entirely. This objectionhas become more and more serious as the burner art has developed,'due tothe tendency in manufacturing burners to increase the heating capacitythereof without increasing their size, this usually being done byincreasing the size of the holes in the burners. This makes the burnersliable to flash back, so that it is extremely important to so controlthe supply of fuel to the burner that'when operative it will burn onlyat. its greatest consuming point, and when the desired heating has beenaccomplished the supply of gas will be completely and instantly shutoff;

With a diaphragm valve, when the diaphragm becomes almost balanced, thatis, when the pressure on the top and bottom of the diaphragm'becomesnearly equal, there is at times a slight leakage of gas through theseat. This prevents free use of such valves, as it has been necessary toselect burners for use therewith that will not readily flash back.

In accordance with the present invention, there is provided aconstruction making it possible to utilize a thermostatically controlleddiaphragm valve as a true snap-action valve by delaying the unrestrictedpassage of'gas from such valve to the burner.

In the accompanyin drawings there is shown, for purposes of illustrationonly, one preferred embodiment of the present invention, it beingunderstood that these drawings do not define the limits of my invention,as changes in the construction and operation disclosed therein may bemade without departing either from the spirit of the invention or thescope of my broader claims.

In the drawings: 1

Figure 1 is a diagrammatic side elevational View, partly broken away andpartly in section, illustrating one embodiment of the invention; and IFigure 2 is a detail sectional view on the line IIII of Figure 1,looking in the direction of the arrows.

The invention is illustrated as utilized in connection with a hot waterheating system, but it will be understood that this use is illustrativeonly of one of the many uses to which the invention may be placed.

In the drawings, there is shown a hot water reservoir 2 having a coldwater inlet 3 and a hot water outlet 4. The water is adapted to beheated by a heater 5 coo-perating with the hot water circulating pipe 6,as is customary in the art, the heater having any desired form of burner7.

Extending into the reservoir 2 is a portion of the thermostat for thethermostatic valve 8. This valve may be of any desired construction, butis preferably of the general construction illustrated in my Patent No.1,107,549, dated August 18, 1914, adapted to open as the temperature ofthe water in the reservoir increases. This valve is adapted to controlthe flow of gas, or other fuel, from a main supply pipe 9 to the chamber10 above the diaphragm 11 in the casing 12. With the main supply valve13 and the auxiliary valve 14 open, the gas is free to flow from thesupply pipe to the inlet of the vali e 8. If this valve is open, the gaswill pass through the pipe 15 to the chamber 10 as described. This willbuild up an operating pressure above the diaphragm 11, tending tomaintain the valve disk 16 carried thereby in contact with the seat 17to prevent the flow of gas from the inlet 19 to the outlet 18. As thetemperature of the water in the reservoir 2 decreases, the valve 8 willbe closed to cutoff the flow of gas to the chamber 10, and

thereby permit the diaphragm 11 to raise to permit the flow of gas tothe outlet 18. Normally, this outlet is directly connected to the burner7 for feeding fuel thereto. It will be apparent, however, that atcertain times during the operation of the diaphragm, as

when the effective pressure above the diaphragm becomes nearly equal tothe effective pressure'below it, and the valve disk 16 is attempting toclose communication between the inlet and outlet, there is a. tendencyfor a slight amount of gas to leak by the seat 17 to the burner. Thiscondition obtains whenthe thermostat operates to open valve 8, due to anincrease of temperature in the part being controlled above that desired,whereby gas pressure is transmitted from pipe 9 to the upper side of thediaphragm 11, or at a time when the temperature of the water in thereservoir has dropped below that desired and the thermostat is justclosing the valve 8 and thereby gradually reducing the pressure abovethe diaphragm 11. In other words, this operation is apt to occur justbefore an increase in gas supply from a condition in which only thepilot has been operating and also at a time when a full supply of gas isbeing cut olf from the burner 7 the periods corresponding respectivelywhen there is a flash back in the ordinary burner. With certain types ofburners this operation is dangerous, as it tendsto produce anobjectionable flash back.

By the present invention this operation in accordance with the usualpractice is made impossible, and a true snap action operation issecured. This is accomplished by connecting the outlet 18 to the inlet20 of a second casing 21 having its outlet 22 connected to the burner 7.This casing is provided with a similar diaphragm 23 carr ing a valve 2%cooperating with the seat 25. his second casing is provided with a smallair relief opening 0 above the diaphragm to permit free movement of thediaphragm.

For the purpose of illustrating the operation of the present system, itmay be assumed that the diaphragms are not adapted to lift until thereis a pressure underneath them of substantially one-half inch of water,and that the effective pressures above and below the diaphragm 11 are sonearly balanced that there is a small leakage to the outlet 18. Thisleakage would not pass the valve 2 1-, but would be delayed thereb andgradually build up a pressure in the in et 20. By the time a pressurecorresponding to onehalf inch of water column has accumulated under thediaphragm 23, there is a corresponding back pressure on the valve 16.This back pressure causes the diaphragm 11 to lift rapidly and in turnsupply a full head of gas to the under side of the diaphragm 23. Thisinstantl raises the diahragm 23, giving a full ow of gas to the urner.

The operation before referred to occurs by reason of the differentialareas of the diaphragms subjected to pressure built up by the leakage ofgas. In accordance with the embodiment illustrated, the central portionof the diaphragm which cooperates with the inlet has a smaller area thanthe annulus which is in communication with the outlet. It will be notedthat the connection between the valve casings communicates Lea/ear withthe outlet of the first valve and the inlet of the second valve.Therefore, a given accumulated pressure in this connection when greatenough to lift the diaphragm 11 will not be enough to lift the diaphragm23] This insures complete opening of the diaphragm 11 before thediaphragm 23 moves at all, and this complete opening then subjects thediaphragm to a full head. During the closing operation, the minute thediaphragm 11 moves to closed position to thereby relieve the diaphragm23 of the full pressure, the diaphragm 23 closes quickly due to theconstruction of the diaphragm, as well as the force of gravity. It willthus be seen that a true snap action is obtained.

The reverse operationis also true. \Vhen the burner has operated for asufficient length of time to raise the temperature of the water in thereservoir 2 to a point at which the valve 8 is opened, a graduallyincreasing pressure is built up in the chamber 10. When this pressureexerts an effective load on the diaphragm nearly equal to theeffective'load exerted upwardly on the diaphragm by the gas in the inlet19 so that the Valve 16 becomes nearly balanced, the flow of gas to theinlet 20 of the second diaphragm valve will be restricted to a pointthat will not givethe necessary pressure for holding the diaphragm 23raised. It will therefore instantly lower, causing the valve 24: toengage its seat 25 and quickly cut off the'fiow of gas to the burner.llt willthus be seen that a substantially true snap action valve isprovided. v

If it is desired to provide a continuous pilot, suitable connection maybe made with the pipe 26 through a valve 27. In order to conserve anygas within the chamber 10,'a second pilot 28 may be provided connectedto the pipe 15 through the controlling valve 29 It will be apparent thatthissecond pilot 'Wlll always have a full flow of gas when the flow tothe main burner 7 is cut off, and will be put out of operationautomatically when a gas flow is established to the burner 7. While itmay be efi'ectively used for lighting the burner, it is sometimesdesirable to provide a continuous burning pilot as before set forth.

This application is a continuation in part of my earlier applicationSerial N 0. 727,709, filed July 23, 1924.

The advantages of the present invention arise from the provision of asystem in which a pressure operated valve, and preferably of thediaphragm type, is operated as a true snap action valve.

I claim:

1. In a fuel control, a burner, a diaphragm valve controlling the flowof fuel to the burner, and a second diaphragm valve for delaym theunrestricted passage of fuel from t e first mentioned diaphragm Illvalve to the burner, said valves being connected in series andadapted'to be both open while the burner is in operation, substantiallyas described.

2. In a fuel control, a burner, a diaphragm valve controlling the flowof fuel to the burner, and means for initially delaying the unrestrictedpassage of fuel from said valve to the burner and thereafter permittingunrestricted passage of such fuel, substantially as described. 1

3. In a fuel control, a burner, a supply line, a pressure operated valvecontrolling the flow of fuel through said line to the burner, and asecond pressure operated valve in said line for delaying theunrestricted.

passage of fuel from said first mentioned valve to the chamber, saidvalves during operation of the burner being open c011- comitantly,substantially as described.

4. In a fuel control, a burner, a valve operated in accordance withpressure differences on opposite sides thereof, and means for causingthe leakage of gas which takes place past said valve to build up anoperating pressure effective for quickly moving said valve to full openposition, substantially as described.

5. In a fuel control, a burner, a valve operated in accordance withpressure differences on opposite sides thereof, and means for causingthe leakage of gas which takes place past said valve to build up anoperating pressure effective for quickly moving said valve to full openposition, said means comprising a second valve in series with the firstmentioned valve, substantially as described.

6. In a fuel control, a burner, a diaphragm valve having a fuel mlct andoutlet, and a second diaphragm valve comlet, and a second diaphragmvalve communi- I eating with the outlet of the first mentioned diaphragmvalve for collecting gas leaking past said valve and building up an'operating pressure against the outlet side thereof, both of said valvesbeing adapted to be open under predetermined pressure conditions,substantially as described.

8. In a pressure system, a burner, and a plurality of diaphragm valvesin series with said burner, one of said valves cooperating with theoutlet of the other of said valves to build up an operating pressureagainst the outlet side thereof, substantially as described.

9. In a burner system, a burner, a diaphragm valve controlling the flowof fuel to said burner, said valve having an inlet and an outlet, and apressure operated release means cooperating with the outlet of saidvalve to collect gas leaking thereby for building-up a predeterminedoperating pressure against the outlet side thereof, substantially asdescribed.

10. In a fuel control system, a burner supply line, a burner suppliedthereby, a plurality of diaphragm valves connected in series in saidline and in advance of said burner, and'means' cooperating with one ofsaid valves for varying the pressure effective against one side thereof,said valves both being adapted to occupy open position during periods ofoperation determined by the operation of said means to thereby permit anunrestricted flow through said supply line, substantially as described.

11. In a fuel control system, a burner supply line, a plurality ofdiaphragm valves connected in series in said line, and a temperatureresponsive control for the first of,

said valves in series, the second of said valves being controlled by thepressure fluid passing the first valve, substantially as de scribed.

In testimony whereof I have hereunto set my hand. a

GEORGE A. ROBERTSHAW.

